The current office chairs are generally given the feature of ascending and descending. For instance, the patent document with its publication number CN101803834A discloses an office chair with a rotatable chair plate. The office chair is composed of a chair plate, a back plate and a leg frame, wherein a chassis is arranged at the bottom of the chair plate, a telescoping member is arranged between the chassis and the leg frame, a chair height adjustment rod is arranged on one side of the chassis and also arranged on the chassis through a rotating shaft, and the other end of the chair height adjustment rod is in compression contact with a telescoping rod of the telescoping member.
The locking and unlocking states of the telescoping member are controlled by rotating the chair height adjustment rod. When a pressure is exerted on the chair plate, the chair height adjustment rod is raised up and the chair body descends; the chair height adjustment rod is released when the desired height is reached by adjustment; the chair body is fixed at the current position since there is a compression effect between the chair height adjustment rod and the telescoping rod of the telescoping member. In the absence of the pressure, the chair height adjustment rod is raised up and the chair body ascends; the chair height adjustment rod is released when the desired height is reached by adjustment, and the chair body is fixed at the current position.